Common-battery telephone-exchange system.



T. G. MARTIN.

COMMON BATTERY TELEPHONE EXCHANGE SYSXEM.

SHEET l.

Pacntvd June 2 APPL.iCAT|0N FILED DEC. 16, 1G05. 1,188,804.

3 SHEETS- J Q i@ wllhllilillmh T. G. MARTIN.

COMMON BATTERY TELEPHONE EXCHANGE SYSTEM.

APPLICAUON FILED DEC.16, 1905.

IMOIITM Jun 52T, NHS.

3 SHEETS,Y SHEE! 2.

Je ,f

fk/., E, awww,

T. G. MARTIN.

COMMON BATTERY TELEPHONE EXCHANGE SYSTEM.

APPLICATION ETLED DEC. I6. 1905.

Patr-umd June 27, 1916.

T13 LEGT G*z MAE FIRST Th rangement whereby ne had between. the :im and distinct and '1115s, namely zin au- Lngc :md :L manual "a )ix-usent application il and claimed certain nffcwfizxiy in order l'ritm'y automatic n', and ilie imzzri'nngenients, to liv-MM!) snlfsciibers elle;

1 Kennin@ telephone cX- :f-z mung telling devices nml, uilwi useful ends, "Eleni in milliers hereinafter "innnnlienlly the vilifn one of the 'um' im; improved l ignllml :i sccnml this lig-- :mun #400, and a Sivit-selector A at MX, :i cniinecor C to SvlifctmD to im nmneniily Fiji. Q shows poi-spostiw, ni-ctn in :L 1; relativ? posiz they :im a mn-mugnclic meta-F; :mil the :im :also shown uw lle Switch.

@imi-imm of lilik? lauw :m' iM-Hl@ gw SIYlli-StutinniHOO, nl; mm: rnv-grilled by the l; hwk '3 laivli is mnd@ with lili#- fxims 31 4, 5 and G.

i ai #nifl Station com- ,in lim-wml hnfs in Seiivs, nml primary winding 0l' they inmultim? il, u couple o ML-iliona exclisangc,v

`ground-post 22.

cuit is maintained closed or opened, depending upon whether the hook is up or down. Said hook is suitably pivoted at its inner end 15, and is forced to rise whenever the weight of the receiver 1H is removed from it, by a suitable switch-hook spring not shown. The secondary circuit comprises the said receiver 16 in series with the secondary winding 1T of the induction-coil S in a permanently closed local circuit. The ringer circuit at said sub-station includes the ringer 1S, the ringer circuit springs 1S) and 20, and the condenser 21. This circuit, while the switch-hook is down, is closed by the calnarm 4 that presses the ringer circuit springs 19 and 20 into contact. and is normally bridged across the main line. lhilc the hook is up, however, the said' bridge is open, because the said springs l!) and 20 spring apart after the cam-arm 4 is removed from the spring 1f). The cam-arm 5 controls the continuity of a ground circuit between the so-called ground-post 22 and the ground terminal G1, through the medium of two springs 23 and 24 that are included in said circuit. The sub-station has three other springs 25, 26 and 27 which are known as the release-springs and by means of which the main line-conductors may be grounded simultaneously for the purpose of restoring the exchange apparatus. lVhen the hook is depressed, as it descends. the said releasesprings are forced together by the cam-arm 3 which latter then engages the laterallyprojecting extremity 28 upon the spring 25.

The engaging portions of the cam 3 and spring 25 are constructed with their surfaces at an angle with each other, so that when the hook goes down one surface of the projection 28 is engaged and when it rises the opposite surface comes into use. In this way, when the hook goes down, the spring 25 is forced onto the springs 2G and 27. and when the hook rises it is shoved in the opposite direction. '1`lu,refore, at the limit of each stroke of the hook, the cam-arm 3 clears the spring 25. The calling device employed by the subscriber comprises two push-but` tons 29 and 30, two contact-points $31 and 32, two springs and 34 and the .so-called The spring 325 and contact 31 are normally in contact, as well as the spring 34 and contact 32. But when the button 29 is pressed the spring 33 is separated from the contact-point 3l and connected with the ground-post 22, and when the button 30 is pressed the second spring 34 is pressed onto the same ground-post, after said spring leaves the contact-point 32. It will be understood, of course, that any suitable means can be employed for regulating the transmission of impulses over the line circuits, so as to obtain the desired results and the described mode of operation. For example, suitable and well-known means can be provided for insuring a proper transmission of current when the receiver 16 is placed on its switch-hook,

In Fig. 2 the first-selector A is shown with the bank 5() of trunk-line terminals 5l beneath it, while the private-bank of private-lmnk line-terminals 53 is located just above said bank 50. ll`he vertical switchshaft 51 is disposed on the front of the switch-frame and retained connected there-- with by bearings which are not shown. The shaft may be moved longitudinally in said bearings. and then rotativelv` by ratchet and pawl mechanism. The longitudinal movements. when the switch first comes into use, are always produced before the rotary motion. ,Among the functions of the shaft that of ay holder for the line-wipers 55 and 5U, and for the private-wiper 5T, is an important one. The former two comprise a set distinct from the latter, but both sets are within range of the contacts of their respective banks 50 and 52. Said wipers are not only insulated from the shaft, but from each other as well. Among the details that are associated with the shaft is a cam piece .78 which is of a split sleeve design and secured to the shaft by a screw 59. The general shape of said cam` in section at right angles to the shaft` is that of au elongated oval with the sharper apex at the side farthest away from the screw 5S). Said cam abuts on a hub (i0 that is shrunk to the shaft near the middle of the latter. This hub carries a set of longitudinal teeth (l that serve, as will be disclosed, to enable the forward rotation of the shaft, and as a locking means against backward rotation of same. ()n the neck portion of said hub there are formed a set of circular teeth ($2 that serve as a means through which the raising of the shaft is accomplished. and for locking it when raised. These circular teeth are traversed by a groove (325 into which the end of a co-called shaft-rest (H normally projects; but when the shaft is rotated any one of the circular teeth (32 which may be, at the proper height slides onto the end of said rest. The end of said rest, of course, is adapted to fit the grooves between said circular teeth. lts upper surface lies in a horizontal plane, but the under side of the end is chamfered to form a wedge that corresponds to the upper slope of the circular teeth. Above the hub (3() the shaft 54 carries an arm (i5, known as the normal-postarm, and which, while the switch-shaft is at rest, and while the shaft-rest occupies the slot (33, is retained against the normal-post 66 by the coiled spring (37. lrThe said normal-post-arm normally retains an off-normal spring G8 in contact with a contact-point (59, located beneath it; but when the shaft is raised said spring Hexes into contact with a grounded contact-point 70 instead.

Vmim il@ ma gnam uiiot'tcd i@ fm: ii.: it

sniffor some :me used Ixir'xxmf; of tir nasi 74 the. furmv mm?. is the Spring 7, :md the iattif he spring I, wiii respect In tim ground spring 7?., Said springs nwe minprised in energizing ail-cuits nf :imgzisls by means of which the upmaive parts flimt raise and rotate the shaft contloied. The magnet TB, arn'mture Ti, and .5px-inge.: 80, 81 :md mms-finite, im iiiidgfhiwvniwf reay, or irrig cuboreiy it 1 minimi, and the magnet wi its :uuml/uro a4 and springs 85 and. 8f3 is the brugkvieuseiviay which is used im restoring the switch. (if the. opemiwmagnets the magnet 87 is known :if: the 'ixticai- Imgnvi md has hm'- nesseli to it, a w--cz-xiiiaii veafivaiuumlure suppormi by pivots bfi? ou the miller l of arlnuiui'e w is :rif uniud :mii when hc mag nefizniiun Y s 'thv letifacingwpi-ing 9:2 restores :nmnum 11n iig: nmmni pmi tion, Th Unwin] uwv-fis'wnt of the zii-mz? ture is limit in' fixa"y wie pieces o' the umgis :mm iwi ami i Sniai iixxk has nmgwh swim if. fiisii'axbiy pim imi iu:- iiimi mid ammi" in iimii 5- muwmnt Mien z-otznf'm first-fhivf'uwimma supgwi a gwm :,n-zii .c miifm 1103 imc-vin :is the ioni ifi is pimiid so imi it may swirei l "il, 1 vertical md5 iim pzsiu; iln'ougxii iii@ i i mi. On iisfiumi, side: Suid Liouivi @whips into Lm (logia 105 and 10G.I si) atvd and conan-lured that ih@ Vimmw (i 'iO-fi) may opi: nie in mlb junction with the circular teeth while tim s\\'itchsimft is; fammi und in its. normal 10 Lary poitimirx mui sf:- timt ihv hitter (1043i muy copmiuv with tim imigi ,udilmi wii (31 when the Hiwit miam/l. To i'ilc iight of the pivots 10i die: body of the dmibiw down therefrmn is :in arm 10S thrill wma into play dui-in@ the), releasing of die switch. Neal' its exti' LV um? 0n tiff-i ppm :aidu thereof a pin upwzxi'dy.

he first stroke mi' the. .Vxfl'timiarmature im 'tink 97 is drawn away 'fumi tim ing 1m? by CNS, und' dmv @le imlbiwiiogg w wimding-faming if", so tim; tim first 'irmiim' the piece izli'ed by the lim :wm 05 100th,

mli wf ihn' when ting mui him' l ux .uli miium;

wim

7 imi im' 4-ifi' met mii is:

pieces of said magnet, which movement is produced by the rotary-magnet itself. The motion of the armature in the opposite direction is produced by the retracting-spring 117 and is limited by a switch-stop behind the ,so-called rotary-arm 118. This arm, like the vertical-arm, carries a so-ealled rotary-pawl 119. Similarly to the verticalpawl, said rotary-pawl norn'ially rests against a stop that retains it away from the longitudinal teeth, and when the rotaryarmature is attached said pawl is drawn into engagement with the longitudinal teeth by a spring 120 that is attached between the rotanv-arn'i and the rear of said pawl. By the time that the rotary-arnniture strikes the pole-pieces of the rotary-magnet. the rotarypawl also strikes a stop or bumping-post that locks the shaft against further advance by the force of its own momentum. At the end of the first rotary step thc dog 10G falls behind the first longitudinal tooth, so that when the rotary-pawl falls back the shaft is retained. lt will be seen that as the shaft is rotated the vertical-dog 103 is withdrawn from the groove of the circular tooth which has been resting upon it. by the engagement of the rotary-dog 10V with the longitudinal tooth over which it has to slide: but at the beginning of the rotation the tooth which has been caught by the vertical-dog slides onto the shaft-rest (i4, and in this way the shaft is still held raised after the rotation begins. The rotary-armature is provided with a, .sd-called interrupter-finger 121 that separates the interrupter-springs 122 and 123 whenever the rotary-armature is attracted, and also with a rotary-armaturefinger 12-1 that exercises certain controlling,` influences over the armature 125 of the last one of the operative-magnets, namely, the private-magnet 126. The said privatearmature 125 works in a vibratory manuel; about a horizontal axis that passes through the supporting point 12T. lt is formed with a f1rwar1ily-projecting arm 12S, the latter having two flat surfaces in an approximately horizontal plane. l `lnthern1ore, the end of the said arm is bent at a right angle downwardly and carries certain mechanical details, namely, a lateral arm 125) which is designed to control circuits comprising the pri\atesprings 130, 131 and 132, and a tooth-escapement which includes two flexible springs 133 and 134 each of which is riveted by one end to the arm 123, one on the upper side and the other on the lower. The upper spring is straight and has formed on its end two tooth projections 135 and 13o which extend downwardly, while the lower one is bent down and at a right angle again to the front. This double angle on the lower spring is provided in order that the latter may clear the bent portion of the private-arm against which portion said spring rests with a degree of tension, and also in order that there may be space in front of said bent portion to receive two other tooth-shaped upwardly-projecting pieces 137 and 138 that are formed on the forward end of the escapenientspring 134, and which are sustained in juxtaposition to the upper teeth, but slightly to the rear thereof. A retracting-spring 139, suitably located, holds said armature normally away from the private-magnet polepieee. A well-known auxiliary switching mechanism common to such switches is the so-called side-switch. It is shown in connection with the first-selector A and coniprises an arm 14() which is secured to the switch-frame in such a manner that it may he made to swing about the pivots 141. The right extremity of said arm is drawn out into a' finger 142 that works in conjunction with the eseapement-tceth previously described. Said teeth, in a manner to be described, red nee the outward movement of the side-switch, by means of said finger, t0 a step-by-step motion, which movement is produced by a retraeting-spring r143.

At the base of the finger 142 a lug 144 that is bent to the front is adapted to strike the am at a suitable time. vhenever the shaft is rotated, however, said cam is carried beyond the reach of said lug. Near its left extremity the arm 140 carries a number of wipers 145, 146, 147 and 14S suitably mounted upon a pin 149 and insulated therefrom and from each other. Said wipers are known as the side-switeh-wipers and are adapted to be operated by the private-magnet and escapement device previously explained. If the private-magnet is energized onee the 1)rivate-arlnature is drawn down onee and restored to its normal position. The escapeinent-finger 142 then passes from behind the tooth 131- onto the rear of the tooth 135 at the downward stroke of the private-armature 125 and from behind the latter tooth at the return stroke. As soon as the. eseapement-finger clears the latter tooth the retmeting-springr 143 draws the side-switch to the second position where it is stopped when the lug 144 strikes the cani 58. Immediately then, when the rotary-magnet energizes` the shaft is rotated, and the cam 5S passes away from the lug 144. Then the finger 142 of necessity falls against the tooth 13S, because of the tension in the spring 143. The rotation of the shaft results when the rotary-armature 115 is attracted by the rotary-magnet. At the same time the rotary-armature-finger 124 depresscs the private-armature 125 and causes the finger 142 to disengage from the tooth 138 and to advance against the tooth 136. Then as the rotary-armature returns to normal, when the rotary-magnet denergizes for reasons to be disclosed, the private-armature, upon following thel finger 1" pvrinic menrfingcr 112` to omniprv1l l; f 13G, thus porlnitling the kidvz-fsih h M to third position with the .1 resting against {he} sirh-;\\'i1vlitheir normal positions the .w 145, 1113 117 :intl 11 mi@ with the 001112101 -]'min1; if r in thv orilvi' nnniwl, This www: :is the 1irst posilion o' iw l whirh [inw it will ha r11-wr ila: lltlil lwllllltl 11h lf-@J 1h(` Swonll rumiifm` hotwwn the [wth Vil tively. Anil whrn 11u4 h1 lint'e" in 1hrA r 11 Julio in moll runnin-M115' www@ 1o cm1 u link '11.111111- ohrrvmlo 1 -i hef nina i721, 'l'hrf alouhihlrrutoil, engilgfw wilh tho hmm' .ortiriil and rotary l?? respon-tiroir, :mil

flouhldogwirni 10( is ronatrsiwhfl switrh is in 1hir l piwilion will, if 1 lh-fn ibo while the Shaft if: rotzitml, lli". heilig :Uhu-lm! 1r hl r i111, `is thrust forward nhru pmi! ion,

"1.1 urli' rotated hr 1h(l roilaqn" stunt thu rml o1' rho :111 lslot 62%,;11 whirh limo 1111 11 norlmilposition, `l

:m11 1 whom Civ spring 249, at one side of the pivots 250. conlt frm to like parts of the first-selector side- .s itch. while the member 251. link 252. sideswitch-wipers 2"55. 254, 256 and 257, together with their corresponding contactpoints 258. 259, 260. 261 and 262. and 263, 264, 265, 266 and 267. and 26S. 26S), 270, 271 and 272. are on the other side of said pivots. It will be seen. therefore. that the connector side-switch-wipers are five in number, while those of the first-selector are only four in number. Among the relays of the connector the \'e1tical-line-relay 273. through its armature 274, can flex the spring 75 .against the ground-spring 276. and the spring 277 toward the spring 27S. when said relay is magnetized. The rotary-line-relay 279, in the same manner. through its armature 260. when the former is magnetized, forces. the spring 261 against the same ground spring 276 and permits the spring 278 in turn to bend toward the former spring 277. Said two springs 277 and 27S are so adjusted that they then collie into contact when the two armatures 274 and 2S() are attracted at the same time. The connector has a relay 282 and a retardation-coil 283 for purposes to'be disclosed. The said relay 282 has an armature 284 by which the backbridge-rel:1y-springs 285 and 286 may be forced into contact. The ringer-relay 267 is a feature common to all connectors of the type under consideration and has the power when magnetized to disconnect the terminals of a called line from those of' the calling line, and to place across the former the terminals of a ringer-generator ll. This operation is accomplished b v means of the armature 23S and the. ringer-relay-springs 265), 290. 291, 292. 293, 294-, 295. 296 and 207. A specially wound ditferential-relay 2l8,with two windings 299 and 300, is secured in the connector for the purpose of accomplishing certain desired functions, which functions will be disclosed later on. The armature 801 of said dilferential-relay 29H when attracted is designed to separate the differential-relay-spring 302 from its mate spring 303. At this juncture it will be remembeied that the release of the first-selector does not occur until the deiinergization of the releasemagnet of the latter. Should the connectorshaft 202 be raised when the release-magnet is energized the release-arlmiture 216, as above stated, pulls the double-dog under the release-link which latter catches the lng 225 and holds saidvdouble-dog out of engagement with the shaft. Said shaft then being free, for the reasons described in connection with the first-selector-shaft, returns to its normal released condition.

Vln Fig. 1 the first-selector l) that is associated with the called line is identical with the first-selector A ot' the calling line 'and needs no explanation since like parts are likewise represented. Then reference is made to the parts of said called first-selector it will be understood that their functions and constructions are the same as those already described for the first-selector A. In connection with the selector D of the called line there are shown no bank contact-s, but they have been omitted for convenience of illustration, and it is obvious that said switch is provided with bank contacts like the selector A. It will also be understood. i of course. that the exchange is equipped with a plurality of subscribers` lines, each of which terminates in a selector-switch such as the selector-switch A\ll such se- 80 lectors are arranged in groups, and the corresponding bank contacts of all the selectors in one group are multiplied together. For example, the first contact of the rst level of each switch-bank in a group are connected in multiple. Likewise, similar contactsl on the rotary side are connected in multiple. and, of course. the corresponding` private bank contacts are connected in multiple. This arrangement of the banks is followed throughout the exchange, not only with respect to the selector-switches, but also in connection with the connectorswitches as well. ln the particular system shown, of course. it is clear that there may be a multiplicity of sub-stations each of which is connected with the central st-ation b v a line of two conductors each of which lines has permanently allotted to it a firstselector. The first-selectors may be sub-divided into groups of one hundred each with all corrcspomling line-banleterminals of a given group connected in multiple. a similar arrangement being followed in connection with the private-bank-terminals. For each level of first-selector line-bankterminals one set of ten trunk-lines is provided with a conductor connected to each one of said trunks. l `or cach level to which a tirst-selector-shaft may be raised its line-wipers are placed on a level with a dill'erent set of connectors for the purpose of reaching subscribers in different hundreds: Each tirstselector is connected with algien set of bank-contact-points in the banks of the connectors of the given hundred to which said first-selector belongs. and when the firstselector comes into use a guarding potential is placed at the c(mnector-private-bank-cmitacts of the line of the callingr first-selector to prevent any calling subscriber from calling this same line. lut while a line is idle a connection with said line is made over the triinleconductors that extend between the connector-lnxnks and the first-Selector.

To re fully understandthe operations and ci ts in connectior with my improved arrangt nt a description will now be given of the apparatus and circuits brought into use in the, system when one subscriber -alls 139 Yanother subscriber, for instance., as illustrated in Fig. 1 when the subscriber :it soir station #400 calls the subscriber at sub-stution #220, which is :is follows: The'subv sc'riber at the callii1g.s1il)-5tntion #mOi-e4 moves his receiver fremthe Switelrhook 2, thus causing,r the ground-springs 23 and 21 to come into Contact :indf comple-tc n circuit between the groundterminnl G* und the ground-post 22, through the said springs 23 und 24 and thc conductors 40() mul 401. In-

1nedintel.\ f`ntter the, rertienl .l'mSh-hutton 2i) is `then pressed twice, then the rotnrr-button 30 once, again the first button 29 twiee. :uid the seeorul but-ton 30 once, and for the v'last time the first button ten time?I` and the Inst hut-ton once. lVhen the spring 33 is forced onto the ground-post twice in Snceession for the first time. the vertical-lineeonduetor 1G! is grounded twice, musing --thc rcrtcnl-linc-relay 71,0f the Erstselector to become umgnetized :md thereby nltrnct its :u'nniture 73 mouwntnrily twiee. The energizing current that pnSSes through Suid ver? tienl linereln-r ot this time enters the -line ntV the ground terminal then purses to the grou'nihpost und Athrough thc spring 321 to the rertienl-line-eoluluctor 402; theuee through t-he rertienl-side-switeh-wiper 117, `ex'm'd'uetxu- 403, rertieulline-relay 7l, eoniluetor 404, bri(lgecut-off-relay-spr]ugs S1 und U2, conductors 105, 40G und 40'( to the non-grounded ter-minnlof buttery vl5 und to grou-nd (l. As u result thc linc-relur-spring K isforeed onto the Agroinid-spring 7T twiee..

*whielr operation closes :i Second mngnetiziner eis-enit tlnjoligh thc rertienl-mngnet S7. 'lhe eurrent in this serond eireuit. enters: the line nt the 'ground terminnl (if: und then pns'qes through the Springs '(7 und 75 to the eon- '"-iluetor 10S :u ulthrough the prirnte-.wprings 121,1 :1nd 1510 und eo'nduetor -lllfl to the vertienl-iungnet R7, pnseziu;r thi-(nigh the eondue tors 410.411, n|12 :mdfl-(l lo the. nml-grounded terminal of lin-Herv l to ground (l. '1 he #100, so thutno sulv'seriher muy he :dile to` eounert with it alter oneit'he irxhxeleetor of said liue'hn heen opernted. 'lhe rertienlline-eouduetor hein;r grounded twice. when the. push-button-i() in turn forces the spr-ingV 34. onto the ground'post 22eme, the rotary'- line--conduetor 413 1s grounded once. An electric current then Hows through the r0- t:1r}'linerelay 72 for n moment, which mzggnetizes `the: said rotary-lilie-relay, causing' the lutter. to attract its armature 74 once, and to -force thel lspring,r 76 against the ground-spring 77 once. 'As n result n second nmgnetizing circuit Ais completed through the private-magnet- 126. The elec trie eurrent in this hitter ense'lows -from the grounded terminal of buttery B to the grounded terminulGz, andthence through the line-relny-Springs 7"( and 70 :incl conf' duetors 411 und 41510 the,private-magnet 126. :utter passing throughwhich it then` palmes through the e .mluctors'-116, 412 und lo? to the non-gromnled terminal of battery l? und to ground (l. -The private-nruuitnre |25 heiner nttrneted once l:md restored imA medintely7 the eSenpement-toolh 137 first velem-s the eSenpeulent-linger I142,whiehflntter then t'n'lls :xgninstthe secondvtotlrii; :md when the nrumture returns to'itslno'rund position this lutter tootlrnlso' clears in turnihe Suid eseapenlent-finger. Atthatn- `Stunt the side-switeh is 'drn'wn intolthe' sec? ond position b v the. retraetingfspri-ng 1113 with the emu-lug;r T1111 restinggainstfthe' eiun 5h. `lt will be understonlthat-"th prongs of the hifnrented cud ofthe. ,linl'r 164 that rexts upon the. T-shnped extrcmitypf the double-dog relensiilg-nrni"108 are (if4 il'f` leient length to permit-the said releasing'l nrm 10H to more from"thcposition thutit vholds when the drmhledogis held normally loelied h r (he release-link 97 tol the position it nxmune when the Suidl double-,dog is rc' leased und` therefore, without disenguging Anid prongs. .\t the moment that the nidoswiteh pannes from the irS( to second position :mother eireuit is completed through the rotnrlr-umgm-t 112, when the-side-Sw'itclr wiper H5 eloses with the-contnct-point 'lhe ein-rent then flows from theground ternliunl (l: to the col'itnet-point lfnnd und 123 and through the second rot-:try mugnct-eoil 118 to the 'conductors 411, 41:'.innd 407 :ino to the, non-grounded termino-l of hnttex- V l :uul to ground G.. The rotarymnenet ll. then n ttrnctsthe ljotnri'orrnrnture [l5 .1nd torres the rotfiuw'pnwl 119 into engngeuxeut with one of the longitl'ulinnl teeth (il. rousing the shaft to rotate one step.\ :finee Suid :ihnft hns nlreudy been ruined.

.lust :1t the time, or :it the instant before the rolzur-:lrnmture strikes the. rotaryningnel polepieren. the roti|r.\"dog"106l fnllS hehind the irst of the longitudinal teeth,"

in the uuumer ulrendi1 deexribed, Ato prevent the shalt from returning to its normal-position when the rotary-magnet becomes deenergized at the instant that the interrupter-nger forces the interrupter-springs apart and destroys the energizing circuit through the said magnet.. This interruption occurs just. 'at the time when ,the rotary-armature strikes the pole-pieces. At the same time that the rotaryawl 119 advances to engage the longitudinal teeth, as described, the rotary-armature-finger comes into contact with the private-armature 125, producing a depression of the latter at the same time that the rotary-pawl produces a rotation of the shaft. As the shaft begins to rotate the cam 5S very soon passes out of reach of the cam-lug 144 and permits the escapement-finger 142 to fall against the tooth 138 before the rotary-armature-finger 124 has depressed the private-armature 125 too far. Very soon, however, t-he said tooth 138 is carried below the finger 142, which latter then falls against the upper tooth 13G vat about the time that the shaft-wipers are rotated onto-the first contact of the second level of their respective banks. As soon as the energizing circuit through the rotarymagnet is interrupted the rotary-armature then begins to return to its normal position, and the private-arn'iature 125 as well, following up the receding movement of the rotary-armaturefinger 125. Very soon the tooth 136 clears the escapement-finger 142 and the side-switch springs into third position with the escapement-finger 142 against the side-switch-stop 150. The shifting of the side-switch takes place just before the i'nterrupter-fiuger permits the interruptersprings 122 and 123 to rengage so that by the time that they do rengage the energizing circuit that has been described through the rotary-magnet has been destroyed between the side-switch-wiper 145 and the contact-point 155. Vhen the motion of the rotary-armature ceases permanently the operation of the first-selector comes to an end, the line-wipers 55 and 5G having seized upon an idle trunk-line similar to the trunkline whose conductors 418 and 419 terminate at the tenth -set of contacts of the second level of the same line-bank. The seized line is protected from further seizure by a guarding potential at the private-wiper and", therefore, at the first Contact of the second level of the private-bank 52 and to all other private-contacts in multiple. Said guarding potential-is established by reason of the connection between the grounded terminal of battery B and said private-contacts through the ground terminal G, sideswitch-wiper 146, conductor 420, back-release-relay 83, conductor 421, and the private-wiper 57. Similarly, should any firstselector appropriate to its use the second trunk-linel of the same level, a guardlng potential will appear at the second privatecontact of the second level of the privatebank 52, as well as of all other privatebanks in multiple. And should a third firstselector seize the third trunk on the same level a guarding potential will also appear .potential is found at each one of the first nine private-contacts of the second level of the private-bank o2. 1f this condition exists at the time that the calling subscriber grounds his rotary-linc-conductor by pressing button 30, the rotation of the shaft will not terminate as soon as the wipers have moved onto the first-terminal of the level to which they have been raised.

The first nine private-contacts being grounded, then when the calling subscriber grounds the rotary side of the line the side-switch trips into second position in the manner described; but then the rotation of the shaft will begin, not to cease, until Vthe wipers have been carried beyond the last of the busy trunk-lines, in this case onto the tenth terminal of the second levell of the banks in question. This operation takes place in the following manner: The energizing circuit through the rotary-magnet being closed, as was pointed out, at the juncture when the side-switch-wiper 145 engages with the contact-point 155, the rotary-armature is attracted by the rotarymagnet 112, and the shaft is rotated one step in the manner described, s0 that the line and private wipers are rotated into engagement `with the first terminal of the second level of their respective banks. At the same time the private-armature is depressed by .the 'rotary-armature-nger and the interrupter-springs 122 and 123 at the end offthe stroke are separated by the interrupter-finger 121. There being a guarding lotential at the first contact Which the private-wiper meets, a circuit is completed through the private-magnet 126, which eX- tends from the grounded terminal of the battery `B through the private-wiper of whateiver first-selector is occupying the first trunk! of the second level in question, through the banlc-multipling-conductors to the contact-point with which the privatewiper 57 has engaged, hence through said private-Wiper, conductor 421, winding of the back-release-relay 83, conductor 420, the side-switch-wiper 146, contact-point 15G, conductors 422 and 415 and private-magnet 126, to the non-grounded terminal of battery B and to ground G. The private-armature is thereby retained in the depressed condition, even after the energizing circuit is broken at the interrninter-springs, and while the rotary-armature-firger Vlil-l returni to its normal position in response to the retracting tension of the rotarv-arniature` spring 117, since the escapement-linger 11.2 is held prisoner by the upper Jforemost eseapement-tooth 13G. The Side-sw;teh-wiper 145 being, therefore, retained in migageinent with the grounded contact-point 155. as soon as the interrupter-springs reirigage the energizing circuit through the rotary-magnet 112 is completed once more. As a result, the rotary-amiature is attracted again, the Shaft. is rotated one more Step. and the private-wiper 57 is moved onto the aeeoud terminal of the second level ot" the privatebank 52. Said Second contact also heilig; grounded the energizing circuit through the private-magnet is n till maintained` so that still the side-switch is not liberated when the rotar.'-armatnre again returns to its normal position. Clearly, then, 'the shaft will he rotated in a relep-lJy-step manner as longr as the private-wiper continues to meet- With grounded private-eontaets. tter having rotated onto the ninth eontiaet. the private-wiper ie rotated one more step into engagement with the tenth Contact ol` the second level ot the private-hanlt: hut this last contact being devoid ot guarding potential, as soon as the. said wiper leaves the ninth contact the rnagnetizing circuit through the private-magnet that has. up to this time, maintained the private-magnet energized is lirolten, Thiboccurs at just about the time when the rotary-armatnre is at the. end ol its forward stroke. so that the privatefarmature that has. up to this time, held the eide-siviteh in its second position. by the magnetizing torce that has now disappeared from the private-magnet. lfalls haek upon the rotarvarmature-li ger and follows Said linger as thi` rot aia-armature returns to its normal position.

lletueen the time that the piiiate-armature is released hy the iirivate-maniet and the time that the rotar,'--arinatnre tolli' regains its normal position. the i;-eapeziieiitlinger l-lzl which. duringr the rotation oi the shaft. has heen resting; against the i'oremobt tooth ot' the upper escapement-Spring, iliaengagreri 'troni said tooth and permite the side-witch to pass to the third poaitiou. lt iS then that the Side-switeh-wiper 145 leaveS the eontaet-imint 157i and paases onto the, contact-point Uitl. This 'disengagement oecnrs inst, hefore the interrupteisprings 1215 and 12?. rengagemo that the circuit through the rotary-magnet is permanently liroken in order that no further notation ol' the ilhatt may take plaee durinf;r in, operation. "he .aide-switehwipers iii ard il# having engaged with the (i iit^.ii-i-}aiiiit-- lti'l and lili. the snhseriherfs line-rondtutore iti; and 113 are ther-eh)v extended through the respective wipers and over the Conductors 423 and .424 to the` rertieal and rotar)v line-wipers 55 and 54'. respectively. Said wipers, being at the, time in engrageinent with the tenth contact'. ot' the second level of the line-bank. place the callingy snheeriher in connection with the ronnertor through the vertical and rotary' trunkconductors `ili and 419. The calling line heine thus extended, when the anharriher prr the vertieal-lmtton 20 twice tor the second digit he again grounds the .'erticalline-conductor lit/L twire and thnS operates the vertifail-line-relav 2T?) ot the. connector C twiee. The path that the enrrent takes from the ground terminal (ll, in this rase. zitter leavingl the ground-post 22 and passing over the vertical-line-eonduetor U2 to the vertieal-line-airle-switeh-n iper 14T then pas-.Seri through the continu-tor #1225. vertical-wiper 55. vertieal-trunk--f'xoinlaetor 40S, vertiral-line--relav 2TH. windingy 'itlt) ot the ditl'erential-i'ela)v i298. conducto a i125 and 42o to the noii-; rou1uleil termiraii oll battery ll to ground (l. 'the \ertical-line-relay of the eonneetor attractsy its armature twice and the latter therehv torres the line-relavspringy ZT-i twice against the grounded spring! Li. .M a result. the vertical-magnet, 211 is energized tiviee in aucceseion, rai:-in; r the conductor ,"al't 120;) one atep at each time h v means ot the vertical-arinatore lill-i aud the vertical-pand 1511i. nthe current through Said vertieal-magnet pasa-es trom the ground terminal tl through springe, .276 and 275. conductor lia private-springs 'Z4-2 and 211. conductors -lzt'ii and 12e'. verticalmagnet 21.1. eonduetor 12S. Side-switchwiper 232i. eonduetors liti. -t'lil and tlti to the non-grounded terminal of latterxv ll and to `ground (l. lt has heen pointed ont that at the tiri-'t movement otK the vertieal-arnl 21;) the release-link 2120 is; ilisengi'aged from the douhle-dmbr 2li) h): the L-shaped piece '.fl l. anfl that the vertical-paul 211' engageS one ot the eirrular tefffth, raising' the shalt so that the vertaal-dog *22 eatrhee trie said :ihat't in a raised poaition. in the same inanner dearrilail in eo* Flection with the tiratialertfa. t the sei-ond operation of the vertieal-arinature the .-'hatt i-i r.. Ad another teo in nhieh new position it is :itill retained h v the same vertioal-dog! 2212. The calling auhseriher next presses the rotaryhutton Il() onee. lgroundinga the rotary-lineronduetor 111i as ahove. and ealusinglr thereby an energizing eurrent to tiow through the rotary-line-relay 27S) of the connector (il for a moment. This eurrent tlows trom the ground terminal (ll. at the sull-station :tt-'hah to the ground-post '2272. thence, over the. rotarv-line-ronduetor 112% and throuli the tiret-selector siile-switeh-wiper 14S. contactpoint 1432. conductor i2-l to the rotary-linewiper 5o, thence o\ er the rotarv-trnnk-collductor 419 and through the rotary-line-relay 279 through the winding 299 of the differential-relay 298, through the conductor `131 and ringer-relay-springs 29() and 201 to the conductors Jf3() and 420 to thel nonground terminal of battery B and to ground (i. The rotary-line-relay, being thus magnetized once, has its armature 280 attracted once, which forces the springs 231 and 276 into contact. As a result, the connectorprivate-magnet 232 is energized, a current through which Hows from ground (1r5 through the springs 270 and 281, conductor 432, privatemagnet 232, conductors 433, 434 and 431. ringenrelay-springs 290 and 291, conductors 430 and -2t to the nongrounded terminal of battery B and to ground G. The private-magnet being energized for the tirst time. the escalwment-tinger 240 clears the escapement-tooth 23T at the downward stroke of the armature 233, and clears the upper escapement-tooth 230 at the return stroke. The side-switch, of course, is brought into second position and stops there as the lug 24T strikes the cani 200; and the side-switch-wiper 253 having then left the contact-point 2:'3 is in engagement with the contact-point 203 instead. so that when the subscriber next presses the vertical-button 2!) ten times and energizes the vertieal-line-relay 273 ten times. the rotar v-magnet 223. instead of the verticalmagnet 211, is magnetized ten times. The energizing circuit through this latter mag net permits thel current to llow from the ground terminal (i5 through the springs 270 and 275, as explained, and then the privatesprings 242 and 241, after leaving which it passes through conductor 420a and the rotaryanagnet 228, and passes over the conductor 435 to the contact-point 203` sideswitch-wiper 253, thence to the non-grounded terminal liay :fry l and to ground (l. The rotary-armature 229 is then attracted ten timeswthat is. once each time, that theI rotary-magnet is magnetized. llach time that it is attracted, thel rotary-pawl 231 engages with one of the longitudinal teeth 207 and rotates the shaft 202 one step in the same way that the, first-selectorrotary-magnet rotates the tirst-selector-shaft.

At the first rotary step the shaft-rest 305 receives the shaft 202, when the vertical-dog 222 is drawn out of engagement with the circular teeth at just about the time when the rotary-dog 223 reaches the crest of the longitudinal tooth over which it has to pass at the time; and by the time that the rotary-armature strikes the rotary-magnet pole-pieces this latter rotary-dog drops into locking engagement behind the said longitudinal tooth and retains the shaft in its advanced rota ry position. At the first rotary step the shaft-wipers, of course. pass onto the first Contact of the Second level of their respective banks; at the second step onto the second contact. and so on step-hv-step until theyv reach the tenth contact of their respective banks. The last step of the calling silbscriber in completing his connection is to again ground the rotarv-lineconductor n-113 once by pressing the rotary-button 30 once. Again the rota r vline-rela)v 2T!) is energized and again the private-magnet 232 attracts its armature 233 once. The shaft having been rotated so that the cam 200 no longer forms an obstruction to the side-switch-arm 245, at the downward stroke of the privatearmature the escapeinentdinger 2lb clears the tooth 230. and when said armature returns toward its normal position the upper tooth 23S is also cleared, at which instant the said side-switch springs into third position. The passage ol' the side-switch- \viper 255 to the third position connects the private-wiper 20.3 with the ground terminal G", when the said side-switch 255 passes onto they contact-point 270. This connection establishes a guarding potential at the tenth private-contact of the second level of the private-lmnk 201 that corresponds to the terminal of the normalconductors 430 and 437 of the called subscriber 220, so that no other subscriber may call in upon said line while said guarding potential exis s. lt will be understood. ot' course. that the same guarding potential exists at all other pri vate-bank-contacts in multiple with the private-bank-contact mentioned. 'l`he calling lirstselector. it will be remembered. places a guarding potential at the private-banks of the connectors of the hundred to which the subscriber #|00 belongs at points corresponding to the line #|00 at the instant that the oll'-iioi-|nal-spring 0S comes into contact with the grounded spring 70. Said guarding potential, by extending to the connector-banks over the privatefnormal-conductor 43S. prevents calling subscribers l'roni entering into connnunication with the calling line over the normalftrunleconductors 439 and 440; and the calling connector. as soon as the side-switch passes to third posiw tion.y provides a guarding potential at the private-bankcontact that correspoinls to the line-terminal of the called line. so that no other calling subscriber may interfere with the completed connection. ln this way both parties. the called and the calling, are rendered sa fe against interference while the two lilies are busy. 'lhe establishment of a guarding potential at the tenth contact of the second level of the private-bank 201 not only protects the called lille from further seizure. but at the same timel forces a current through the bri lge-cutoll'-rela. y 3.30 oll the called irst-selector` which relay. by its armature 35|` controls the brhlge-cutsotl^reA lay-springs 352, 353 and 354. This latter relay, when magnctized, separates the said Springs from eaeh othe and thereby opens up a bridge circuit. normally 'established through the vertical anil rotary line-relays and 356 across line-eoniluetors Ht aiul 442. and at the same time interrupts a ronneetion between saiil relays antl the nongrounded terminal ot' battery B. wliieh terminal is directly connected withthe spring :t5-'1. Since the eontluctoixs` llt anti 4t2 are ineluiletl. one on eat-h siete ot the main talleing eireuit. as will be hereinafter disrloiswl. it is desirable to remore` all nnneeessary bridged connections t'rom between them. tor obvious` antl other reason to obtain they best results.

The energizing eireuit through the briilgrev cutoff-relay fitl extemls troni the gggrouzul terminal G to the eonneetor-shle-switt-lr z-ontaft-point '270. sille-f-witeh-wiper M. eoiniueto" ltt. private-wiper .tl. trunli'- eontlnrtor ttt.apring35T.i-oiit1otpoiiitHitt. liriiir "itotl relay 35o to the non-grouniieii oi1 hattery t?) anal trim in. to gri-ouml (l. \\'hen the Sitte-swlieb-wiper '255 passes into emitart with the `tfi'oululetl eontaet-point 2713. stiii another eireuit i# then tormefl through the ringer-relay 2Q?. whit-h eiuergfixe-z the Sai-'l relay. The eurrent in this eireuit. para z' trom the Same `grounil terminal ti" to the Sitte ritrh-wiper 2.33. eomluetor -l-lfA ringerrelay 29T. eoluluetor litt. litt'ei'entialrelaylHprings 3.0i) anti 303. eoniluf'tor tti. eontaetpoint QR. sitle-switeh-wiper 15ML i ne non romnlerl terminal of battery l to groulul tl. This relay 29T at onee aitrae4 its armature :intl toreefi the ringenrelay-springs ftlo. 292i aiul 2th, away trom eorresfpomling ringer-relay-springs '291. tt anil 20T. reepeetirely. amt into eontaet with other ringer-relay-f-pring. it?. 292. ainl Q95. re Speetiyely. The eiiruiti-` through the vertieal ainl rotary line--relay-` LT aml 2TH. respeetiyely. eaeli time that the vertieal aiul rotary push-buttons lo antl tl hare been pre steil. hare eomprreil in the one ease the wiiulingz` Itlltl of the litl'erential-eoil EUR. anil in the other ease the winding' titl otl t-aitl eoil, rtherefore. in eaeh ease the armature Itll of ywill relay his been att 'teilz but at, this partieular stage the energization ot thia` relay has no :siggnitieam'eA Saul winfiingja otl the ilitl'erential-eoil are .-o wountl that when a euri-ent flow.-y tlirougjli them in series thel rela;y will not energize. but when eurrent ia sent through one winiliir;r only. or through both windings in multiple. the Haiti re'iay will energfixe. lt i-'lioulrl lie ohserretl that the ringer-generator li is eonnei'teil lireetly to the ringer-rehrr-sirings lill azul 197. aiul that miti .Springs are respeetirely normally irli'ilgag'efl with the prlinf l J-fi. ane! SNL i ieri-lore. when the ;-ule-\-\\ileh i in the thiril position. if the ringer-relay were not enereif/eal ringing eurrent woultl pasa ont over the ealleil sulmeriber`- line-eoinlnetors by way ot' the normal-line-rondnetors 436 anil 43T. sini-e the yertieal and rotary Sirloforitrh-wipers*25o anil 25T are then lireetly eonneeieil with ther line-wipem` 203 and 204. respeetiyelr. lt is tor this` reason that speeial provi-ion has been ma le tor the ringerrelay-springs 202i aiul "ltlt'i to separate from the ringer-relay--springs :E14 aiul 25V( at the 'in-tam that the et)nneetor-siile-switi-h passes into thirrl po-ition. The eonneetion between the railing;r aiul ealleil lines having been estalilishetl. the ealling party is now in a position to l\i;'nal the ealleil line by means ot' his siunalingj-hottini 1:'. But before going any farther it will he explaineil that itl t'or any reaiion the ealleil line is busy at the time that the eallinL suliseriber gfrouiuh4 hisy rotary line-f'oniluetor for the lai-t time. to transfer the eonnertorileiwiteh from leeoiul to tliiril ptr-ition. lieeause otb a ji|iar lin r potentia l the ealling ronneetor is thereby relea-,ett l-'or inf-tanre. if the ealleti line #220 hail been ealleil by another eonneetor before the eonneetor tiere woultl have been a j iuarilin; r potential at the tenth privateeontaet of the Heeonil leyel ot the privatelianh gil. eorrei-poinling to the line ot the -uli--stalion 2-2o. Ur. on the other hantl. luul the `ahatl. ot the tirst-seleetor l) otl the ealletl line been outotL its normal poaitionbeeau-1e o1' the operation ot saii i\l|alt by tlu` :oiliserilier :it the faib-ftation #220. or for any other reason. the an|e private-baril(- eontaet wonlil have been eonneeteil to frourul I'rom the iii-taut that the normali:ost-arm i.) permit :he ott-normal-spring 35T to engage in eontzu't with the Lfrouniliul eontaet.- po'nt t'iti. Haiti guai-line potential. in this lasty eaxe. woulil rear-li the eonneetor-privatebanl\V by way olI the pri\ ate-inn'mal-eomluetor llt. A\t any rate. ylioulil the private-wiper .itl tiiul Iui-h a guardingr potential at the instantr that the railing roihseriber grounds his rotary-lineeoinluetor vlt. t'or the last time. the eonneetor woulil be releaa-eil antl Vwoulil not eomplete the eireuil between the ealline line aiul the ile-iretl line. rl`hi.\l release oeeur.-` berause ot' the energjixation ot' the release inaig'net Llf. uiuler stiel; eonilitions. aiul while the Hille-switrh is in ita1 seeoiul poaition. wliieh position is the proper one t'or the ,-iile-switeh liel'ore the last, grountlin; r otthe rotary y i le otI the line. 'the private-wiper H5 hurling' a guarding: potential at the instant that the ealling subt-eriber ,'rounit-A the rotaryline lll. by pressinfg; the rotary-button itl t'or the lasty time. the eolinet'tor i1 thereby releaseil. alnl the sulrrilier tail 4 to malte the ileiretl ronllr't'tloii. ylllie leleawl oeriir beraufae ot the energfixation otI the releaw-inagnet at the instant that the prirate-armature 'll elo-ie:-` the pri\:itenrinlfj.-` Bilt :intl lll :u a result ol' theener; Aingfoltht rotary-line-relzrv2TH.

'l`he energixing r eireuit through the rel lasemagnet permits the current to How from thc grounded terminal ot' batter B to the tenth contact of the second level ot' the privatebank. thence through the private-wiper 205 to the side-Switch-wiper 255, contact-point 205, conductor 448. and through the privatesprings 243 and 244, conductors 445) and 450 to the release-magnet 215 after passing through which it tlows through the conductors 451, 434 and 431, ringer-relaysprings 25)() and 291. conductors 430 and 420 to the non-grounded terminal ot' battery B and to ground (i. The connector-releasemagnet being energized, the release-armature 216 moves the double-dog 219 in such manner that the lug 225 is caught and held in the aperture 227 on the end of said link. (lf course, when the double-dog is thus rotated the locking-arm 223 is withdrawn troni the longitudinal teeth. and the shaft is then free to rotate toward its normal rotary position, owing to the, tension in the coiled springr 210, until the normal-post-arm 209 strikes the normal-post 30G. At that instant the shaft-support 305 enters the slot 307, and the said shaft otl necessity falls to its normal position. The release-armatui'e. upon rotating the double-dog 210, at the same time drives the side-switch to its first position by means ot' the side-switch-link 252 and the double-dog release-arm 224. This latter, by pressing the t'ormer back. forces the escapement-linger 240 back between the escapenient-spriiigs 234 and 2355. and is caught behind tlie rearniost lower tooth 2217. behind which it is retained until the connector comes into use again. The restoration ofthe connector-shatt may take place even whileI the release-magnet 215 is energized; but since the energizing circuit through said magnet comprises the private-wiper 205, and also the side-switch-wiper 255, it will bc evident that as soon as the shaft begins to rotate to its normal position the energizing circuit will he broken as soon as the private: wiper 205 leaves the pi'ivate-contact-point with which it has been engaged. '.lhe saine energizing circuit is also interrupted at the side-switch-wiper 255 when the latter is I'orccd back into its irst position. 'lhe calling subscriber, thinking he has` established connection, presses the sigiialing-button 12 at the sub-station #400. with the result that the spring 1l is separated t'roin the contactpoiut. 10 and closed into connectioirwith 'the grounded contact-poiiit 35. The said spring l1 being in direct connection with the vertical-line-conductor 402. through thc primary circuit-springs 13 and 14, and through the contact-point 2&1 and spring 38, this act grounds the said vertical side of the line as long as the push-button l2 is depressed and magnetizes the veitical-line-relay of the connector; and since the side-switch-wiper 253 of the connector has been restored into connection with the contact-point 25S. the vertical-magnet 211 is energized also. As a result, and for r `asons previously described, theshat't ot' the connector is raised and the spring 30S is brought into contact with the contactlpoint i100. The engagement of these two parts completes a circuit over which a busv signaling circuit. provided by any suitable means represented at F. Fig. 1, is sent over the line to the calling subscriber`s station and through his receiver. Said busy signal will notify him that the desired line is busy. This busy current that is generated in a suitable coil 311 passes from thence to the conductor 452 through the side-switchwiper 254. contact-point 250, conductor 453, springs :10S and 310. conductors 454 and 455, condenser 450, rotaiv-trunk-eonductor 419, rotary-wiper 50 of the first-selector A, coilductor 424. contact-point 162, side-switchwiper 149. rotary-line-comliictor 413, primary winding 7. transmitter f). contact-point 10 springs 11. 13 and 14. vertical-line-condiictor 402. side-switch-wiper 147, contactpoint 101, conductor 423, vertical-line-wiper 55, vertical-trunii-conductor 41S, verticalline-relay 273. winding 300 ot' the differential-coil 29S. back to the coil 2111. The silbscriber then restores his receiver to its hook, thereby grounding both line-conductors 402 and 413 at once. The grounding occurs when the release-cam Il t'orccs the releasesprings 25, 26 and 27 into contact. The. grounding ot' the rotary-line-conductor 413, in this case. energizes the rotary-line-relay 279 of the connector in the usual way. The connection from said conductor to the ground is completed from said ground through the springs 24 and 2:5, conductor 400, through the release-springs 27 and 2G, to the conductor 413.

The energizing ot' the rotary-line-ielay forces the release-spring 27S toward the spring 277: at the saine time. the grounding oi the vertical-line-conductor 402 through the release-springs 25. 20 and 27 energizes the vertical-line-relay 273. which latter then forces the sprinlr 277 against the spring 278` The contact ot these two springs establishes a circuit which conveys a current through the rebase-magnet of the connector and through the bacli-release-rela)Y S3 o1 the tirst-sehctor. The circuit begins with the grounded terminal (1" ot' the first-selectorside-switch andextends through the contactpoint 100. side-switch-wiper 146. conductor 420. lack-release--relirv Sli. condilctor 421, private-wilwr 57. release-truuli-conductor 474. springs 277 and 27H. conductor 450. release-magnet 215. conductors" lili and 4211, ringcr-rcla vs|irings 2510 and 2511, conductor 20. to the non-grounded terminal of buttery li and to ground (i. The release-niagnet becoming niagnetizcd the restoration of the connector results in thc` usual manner..

The. hackrelease-relay 83 becoming enen fixed at they same time forces the hackmeleaorelay'springs: un and rh into contact, "which clones an` ciu-rgixiug ril-Quit through tho rcioatfiiiagnct 111. nt thtl lirSt-Snlnctor. Tho ril-fuit in this; laut marie extends from tlul gruundcfd trrniinal (ll, through theI springs and 8V. rcloanv-iuagnt 111, to they non-gr-inindr-d terminal of hattrriv B and to ground (i. 'lling the rolrasoniagnet ot' thil tii'ft-seiortor attratta itxl armature 9S), and at th@ instant that the @rrr-fixing circuit is (lwtlovvd through the lurk-miras@ rilay.y whrn tho rrlt-aaeprimis at the nul)- statiun ,rt-lili? arfl permitted to `n uirattg the cirruit through tht rrlaswiiiagiiet 11.1 also is dowtrolwd. and thv relouswarniature 99 iuturnf. to ita4 normal position, restoring the tirst-selertor in the uoll--lniou'n manner. At thvy sani time. the r4.lease-armature of the ctinncctor-rnlvaseanagnvt 215 rcturns to its normal position. hinting thv connector in a full norma rondition. But it has heen descrila-d that th@ milinrrilwi' did not lind the linu huny. and that having made a Connection hr. was in a position to signal the called suhsrrihrr. After doing so. he preise?, his signalintrhntton l2 in a manner already stated. und thereby grounds the verticallinoconductor 402. But as noon as tho spring l1 rrat'hvs tht contant-point; 35 the grounding ot thv vertical-line snergizes the vertical-hne-rrlay '12755 and thvl differentialrelay 29S. sinne, the Current in this case )uw only through tho indirig $10() and thence to tin non'grounded terminal of the hattet-y li. is suon au tho dithrenti:1l-relay attrintb' ith arinatnri` 301 thi, diil'ri'entialv reiay-ispring 'U'l is forced :may from the Hiring 302, und as, a Musilli. the ilulglutiZilig current through the fingir-relay, which has lawn drslcrihrd. in intrrrupted at that point. The rinrera'clay becoming duiiiuergizod, tho

y. Springs 2Jfand 2943 thun tall hurl; into con tart with tlu ringer-gnnvrntonrpriugs 294 and 297. rwpvrtively. fis a result, ringing rnrrnnt is proiuted out on the lint of tho vailml aulisenrilwr, which rurrtfnt passes thro his ring'rr for the purpose o nah: him. This rurrent paises troni the gg'nnnratnr li to thil vonduvtor 45S, Springs 2297 and 25H3. rido-su'it li-\\'i}1er 2.37. contartpoint 272, conductor 59, rotarydinn-wiper 204. rotary-normalronductor Y'1137, Qondiur tor H2, Spring' 375, contartwpoint 376, condurtor 1130, ringrrrrcuit'springg 377 and 37?., ringrrr and minimiser 379 and 380, renm'tifuiy. conductor #$1.31, contact-point 381, spring i-r, vri-tiraidilio-Conductor y141, vurtf'alnormalrondiu'tor 43th vertical-Wiper ronduotnr H32, contact-point 271, sidesuitcli-u'iper 25V. springs 2913 and 297i, Condurtor Jft. hawk to tlul irinerator lil, As ymon as thivulling; Suliscrihvr roloabos his signaling-button thu current through the Subscriber remo-van his rereiver 383 from the switch-hook 2184-. the latter, upon rising, destroys the ringing circuit through tho ringer 37S) at the instant that it permits the springs 377 and 78 to separate. lt also forces the primary cirruit-springs 385 and 381i into Contact. closing a circuit. through its own `@tation that provides; the transmitter 387 und primary winding 388 of the induction-ruil 389 with current for intercomniunicating purposes. ters into thi rircuit from the ground terminal thence to this intact-point 270 and side-su'itch-winni' 255, conductor 465, hack#hridgirrolaV 282, ring0r-rtrlity-*springs 295 and 2h13, sidfs-switclrwipnr 357, contactpoint 272, rotary-Iine-wiper 204, normal conductor 187, line-ronductor 142, primary winding 5388, transmitter 387, through the primary circuitfsprings 385 and 386 to the verticaldino-conductor H1, vertical-mirmzilconductor 436, verticaldine-wiper 203, contact-point 271,Side-switch-Wiper 256, ringen relay-springs E293 and 292, retardation-coil 283, to the noirgroundetl terminal of hattery B and to ground G.

"he eiwrgizinp ry current for the talking circuitin panning-,f through the hack-bridgerelay-rnil 2K2, rnergizos said ruil and vannes thc armatuu` 281 to rloso the, haclvhridge-relayrpringn 285 and 2H() together. At the instant that those two springs 285 and 286 rouw into Qontart the callingsub-station is proridod with current for talking purponrs. The rurrvnt in this ifirrnit paises from the non-grounded tt-rininal, of battery B through tho condurtors 126 and 425, winding 300 of tlic ditlrrevitiai-relay-eoil 29S, verthfaldinen rrlay 27.7%, wrtiiral-trunk-ronductor 118` verticalnphr 55 of thn first-selector A, conihutor 423. mutant-point 161, Sidr-switrhwiper 147,wrtiral-linQ-roiulurtor itlgspring rontartnpoint 31, condurtors ltit' and M17. primary rii(:iiitspx^iiigs 14 and i3, spring 11. rnntartqioirit 10, transmitter 9, primary nindiihgr 7 ot the inductitmroil 8, romlurtors 468 and 469, contact-punit 32, spring 3l, rotary-lino-conductor 113, sidesu'itch-wiper 14S, contact-point 1132. ronductnr 424, 1'otaryline-\\'ipor 56, rotarytrunk-fonduvtor Allfl, rotary-linwrrlay 271), windinr 2th) of the (liti'tnontial-rtlay 298, uomini-tor 131, ringrr-relay-springs 25N) and Q89. rondurtor 170, hack-hridge-rrlaysprings 2ST) and 286. conductor 405i. sidesuitrh-uiprr 255, tothe 2ground trrxninal G". It riil he noticvd that the two windings` 2.9i)

Thel current en- 'vvntral or and 300 of thv ditl'erential-voil 29S are iuvludvd in the virvuit that provides the valling subsvribvr with thv vurrent t'or talking purposes. l`his vurrvnt. sinvv it passes through thv windings ot' thv ditl'vrvntial-rela \v in serivs. dovs not vnvrgizv said relay. Sinve thv talking virvuit vurrvnt to thv valling station pa ses to the main line-conductors 418 and 419 through the vvrtival and ro` tar)v line-relays 2TH and 2T9` these two rvlays, as soon as said virvuit is vstablishvd, bvvomv magnvtizvd and attravt thvir respvvtire armatures 2Tland 290. This boing thv vasv the rvlvasvsprings 2TT and 2TS. whivh arv undvr thv vontrol oll said line-relays, are brought into vonnvvtion. and .thv vonnvvtor would bv rvlvasvd wvrv it not for the t'avt that thv vonnvvtion bvtwvvn the rvlvasv-magnvt 215 and thv non-groundvd tvrminal ot' thv battvr \j l is intvrrupted bvtwvvn the ringvr-rvla \'-s|rings 299 and 291. whilv thv ringenrvla \v 2ST is vnvrgizvd. llndvr thvsv vonditions, thv primar)Y windings T and 35S otl thv sub-statious #40() and #229, respectively. arv vonnvvtvd in svrivs iu a virvuit through thv rondvnsvrs 45t) and 4Tl. Said virvuit vomprisvs in svrivs the primar)v winding T, transmitter 9 ot the sulrstation #490, thv primaryv virvuit-springs 125 and 14, rvrtivallinv-vonduvtor 402` first-svlvvtor-sidw switvh-wipvr 14T, line-wipvr 55, trunk-vonduvtor 418. vondvnsvr 4T1 -ot thv connector (l` thv vonduvtor 4T2` ringing-rvlily-springs 292 and 293.sidv-switvhwipvr250, line-wipvr 2915. normal-ronduvtor 4256, rvrtivallinv-von dnvtor 441, primary virvuit-springs 386 and 385 ot' the sub-station #229, transmittvr 3ST, primar)v winding 388, rotary-line-vonduvtor 442` rotary-normal-vonduvtor 43T, linv-\\'ipvr 204,siilvswitvh-wipvr 2.'1T,ringvrrvlay-springs 299 and 295, vondln'tors 4Tll. 455, vondvnsvr 4.36, trunk-vonduvtor 419. rotary-linvwipvr 5o. sidv-switvh-wipvr 14h', rotarly-linv-vonduvtor 413. and bavh to thv primary winding T. "lhv rvvvivvrs lt and 353 ot' the two sub-st.1tions in question arv in serivs vavh in a loval virvuit. with thvil' rvspvvtivv svvondamY windings IT and 399 otl thvir iinluvtion-voils and 391k and in a rvr)v wvll-l no\\n and tamiliar mannvr thv two subsvribvrs ma)v volnmunivatv `with vavh othvr, sinvv thvir primar)v virvuits arv vhargvd with a suitablv vurrvnt from thv vommon battvry l. Thv vonnvvtion bvtwvvn thv two subsvrihvrs having bvvn vstablishvd. it may thvn bv dvstroyvd or opvnvd from thv valling sub-station` by thv simultanvous grounding ot thv rvrtival and rotary linv-volnlut-tors. Should thv subsvribvr at sub-station .#400 rvstorv his rvveiver thv rvlvasv-spriugs 25, 26 and 2T, voming into vontavt, would plavv thv vvrtival and rotary line-vomhlvtors 492 and 413 in vonnevtion with ground at the grounded terminal G'. line-conductor produvvs a low ot' vurrvnt through thv rotary-line-relay 2T9 and thv winding 299 ot thv ditlervntial` relay 295. This is brought about by thv short-virvuiting of through ground. ning with ground ground-springs 24 spring 2T spring 26 through thv snlv-switvh-wiper 148 ot' the first-selevtor A, rotary-line-wiper 56, vonduvtor 419, rotary linerelay 2T9, winding 299 ot' the dit'l'vrvntial`rvla \Y 298. vonduvtor 431. ringvr-rvlay-sl)rings duvtor 4TH. havlvbridgv-rvlay-springs 255 and 299. vonlluvtor 495. side-switch"wiper 255 to thv ground terminal (11, Thv rotary linvfrvlay bvromvs dvvnvrgizvd, and thv rvlvase-spring 2Tb` rvvvdvs spring 2TT; and sinvv only thv winding` 800 otI thv ditfvrvntial-rvlay 29h' is rvvviring an)v vurrvnt. said rela)v 29h bvvomvs magnvtizvd. The vurrvnt-tl .-w through said rvla)v vxtvnds from ground 29 and 25 402, si lv-switvl1-\vipvr 14T. vonduvtor 423, line-wiper 55. vonduvtor 41H, \'vrtivallinv relay 2T3. dill'vrvntialwrhiding 399, to thv non-groundvd terminal ot' ground (l.

The vnvrgization otl thv ditl'vrvntial-rvlay, as above, produvvs a dvinvrgixation ot' thv ringer-relay 28T whivh. upon restoring its armature to normal ringvr-relay-s]n'ing 299 to separate from the spring 289` and to return into vngagvment with the spring 291, Tln,- vngagvmvnt ot these last two ringvr-rvlayaaprings 29() and 291 establishes i through the svvond (litl'vrvntial-winding 299 ot' thv ditl'vrvntial-rvlay 29S, and vurrvnt in this way passes through said voil in suvl; a direvtion as to rvint'orvv the winding 300; and, thervforv, bvvomvs dvvnvrgizvd, thv ditferential-rvlay vontinuvs to rvmain vnvrgizvd as long as thv release-springs 25,

vvssa tion otI the This short-virvuit, begin- (l, extends through thvI and 23 to the releasealnl thvnvv through the release- 26 and 2T remain in vontavt. The nnwnetlzinff vurrvnt through thv h h t* last diTervntial-voil in question passes from 115 the ground terminal (l1 to thv rotary-linevonduvtor 413, thvnvv through the rotaryline-rela)Y ot the vonnevtor and ditfvrential` winding 299. ringer-relay-springs 290 and 291 to the non-grounded terminal of battery' 120 B to ground (l. l `urthvrm0re, at thv instant that said ringer-rel:xy-springsl resume thvir normal engagement, and simultaneous with the reinergization of the rotary-line-relay 279 of the connector, the release-springs 27T 125 and 2TS under the control of the line-relays of sind connector are forced into engage ment, once more, slnce both sind relays are The grounding of the rotarythvsv two rvlays in series to thv rotaryline-conductor 413, 75

299 and 299. von- Jfrom thv releaSvto thv rvlvasv-springs 2T, 90

battvr)Y l and to position, permits thv an energizing virvlut again vvvn at'tvr thv ringvr-rvlay 110 energized at the time. The engagement of said springs, in the manner already pointed out, produces the energization of the release apparatus of the coiinectorand first-selector, releasing said switches. It will be clear that as soon as the connector-private-wiper disengages from the private-contact-point with which it has been in engagement. the bridgecut-Uf-relay 35() of the first-selector l) is then restored to its 'normal position, with the springs 352, 353 and 354 in contact, lea ving the said first-selector in a condition to be operated by the sub-station #220. At the saine time that the private-wiper leaves its coiitact-poiiit the line-wipers 203 and 204 also leave their contact-points, and as a result the circuit conveying energizing current for talking purposes to the substation #22() is also destroyed, causing at the same time the deenergization of the back-bridge-relay 282. rl`his relay as soon as deenergized permits the springs 285 and 236 to resume their'normal position; their separation produces no etl'ect, since their influence is destroyed as soon as the ringer-spring 290 separates from thel ringer-relay-spring 28S). llad the subscriber at sub-station #220 restored his receiver C583 to the switch-hook 3%1 before the connection was destroyed between the two sub-stations, the separation of the primary circuit-springs 885 and ltlti that would have resulted would have then caused the cessation of the fiow ot' current to the sub-stations for talking purposes, rThis is evident. because as pointed out the circuit providing current at the sub-station #lim is controlled by the back-l)ritlge-relay-springs 2h23 and 256. Said back-britige-relay is in turn under the control of the called subscriber and in series with the primary circuit-springs ISST and Jlht; therefore, when said springs are permitted to separate. the circuit through the back-liridge-relay is destroyed, and as a rcsult the current that flows to the sub-station #40() is interrupted, which current, as has been pointed out. flows only .when the springs 2ST and 256 are in contact. lt has been fouml in practice that good results are obtained when the connector-linc-relays 279 and 275i are wound to a resistance of 125 ohms cach` in series with the windings 29!) and 30() of the differential-relay 298 of 25!) ohms each. Also the back-brilige-relay 282 and back-bri(ige-retai'dation-coil 283 may be -ouml to a resistance of 375 ohms each.

'l`hus it will be seen that iii the arrangement of circuits, to obtain the foregoing results, the private wiper 205 is connected in multiplc with the ringer relay 287, which relay therefore encrgizes when the side switch isses to third position and remains energizcd during talking. Again, the busy-release-circuit#tliat its to say, the circuit by which the connector is automatically released when an attempt is made to set it on a busy line-includes contacts of the ringerrelay, these contacts being normally closed. Furthermore, it will be seen that this private-wiper 205 is also employed for establishing a guardingr potential for any called line with which the connector makes Connection, and combined not only with the said ringer-relay. but also with the doublewound relay having,r the coils 209 and 300, substantially as shown and described.

'itli the arrangement shown, the backbridge-relay 282 of the connector is connected to the rotary-line-coiiductor at a point between the condenser -i.`iti.aiid the ringerrelay springs, the circuit of this back-bridgerelay including tour springs of the ringerrelay. Again, it will be seen that the said private-wiper, which is new in a connector of this kind` gets current from the saine, ground that gives current to the coil of the ringer-relay, namely the ground tir extending from the third Contact 270 of the sideswitcli. ln addition, it will be seen that the upper ringer-relay spring 289 is connected directly with the spring 255 of the back-- bridge-relay so that the called .subscriber can control the supply of current to both lines for talking purposes, thus insuring against any undesirable waste of current.

Vln other words, no current for talking pnr` poses is flowing through the calling subscribensl line until after the called subscriber answers. It will also be seen that the backbridge-relay is so connected as to enable the called subscriber to put talkingr current on both lines through contacts of the ringeri'elay. Another feature consists in the said private-wiper 255 of the side-switch. which wiper is connected with the shaft privatewiper 205, the ringer-relay-coil 287, the back-bri(lgercla.\'-coil 282. and the spring 2h23 of the liack-bridge-relay. Furthermore, the side-switch private-wiper second contact. is only connected with the normally-open spring of the private-magnet, and arranged in combination with the new connections for the side-switch private-wiper.

lin connection with the subscrihefs substation apparatus` it will be seen that the rcceivcr has a circuit which is totally independent of the main line-circuit. inasmuch as the receiver is only iiiductively connected with the main line-circuit. 'ith this arrangement, tlie ringing-key is in the circuit of the transmitter. but not in the circuit ot the receiver. With this arrangement of the subscribei"s apparatus. the construction is very inuch simplified, and l find that better results are obtained in various ways.

lVith further respectl to the exchange apparatus` l believe I am the first to provide a ringing-relay which is energized continuously and necessarily during conversation between two automatic telephone exchange subscribers, in order to maintain the continuity of the talking circuit, and in a comiiiereially successful system.

It is obvious that the resistance of the variouscoils, relays and magnets can be adjusted and changed to suit the conditions of any particular case, and without departing from the spirit of my invention.

It will be understood that the selectors herein described and illustrated can be of tlie general type disclosed in Patent No. 815,321, granted March 13, 190C, to Keith, Erickson and Erickson. It will also be understood that the connectors herein referred to can be of the general type disclosed in Patent No. 815,176, granted March 13, 1906, to Keith, Erickson and Erickson.

What Ir claim as my invention is 1. A telephone exchange connector provided with a line-condiictor, a condenser in said conductor, a ringer-relay having a nor- Inally open spring in which said conductor terminates, and a back-bridge-relay having one terminal connected with said line-conductor at a point between the said condenser and the said spring, together with means controlled by said baCkbridgerelay, and under the exclusive control of any called subscriber, for supplying current ,for talking purposes to the calling line.

2. A telephone exchange connector provided witli line-circiiit-condiictors each having a condenser therein, and a back-bridgerelay located on the side of the condeiisers toward the called subscriber and adapted to be controlled exclusively by the latter, means dependent upon the eiiergizatioii of Said relay for supplying talking current to the calling line, and a ringer-relay having at least four normally open switch-springs, together with an energizing circuit tor said back-bridge-relay, said energizing circuit including said springs.

il. A coniiion battery automatic telephone exchange connector provided with a differential relay and with a private wiper, together with private bank contacts adapted to be engaged by said private wiper, a second relay and means for energizing it over a local circuit during talking, one relay controlling the other, connections betwceii the second relay contacts and said private wiper, and means whereby the private wiper prevents connection of the contacts of the energized relay with a busy line.

4. A common battery automatic telephone exchange connector provided with a ringerrelay having normally-closed ringing switch-contacts, and with a private-wiper, together with privatc-bank-contacts adapted to be engaged by said wiper connections between the relay contacts and said private wiper, means for energizing said relay during talking, and means whereby the privatewiper prevents connection of the contacts of said relay 4with a busy line.

A common battery automatic telephone exchange connector provided with a ringerrelay having noriiially-opeii switch-contacts, and adapted for constant energization during use of the connector for talking pui'- poses, together with a'relay and means controlled thereby for putting current for talking purposes on the line of the calling subscriber, said relay being exclusively controlled b v the called subscriber.

t5. A common battery automatic telephone exchange connector provided with a sideswitch having a private-wiper, a shaft having a private-wiper, a ringer-relay having an energizing coil and a set of switchsprings, and a laick-biidge-ielay having an energizing coil and a set of switch-springs, together with connections whereby the said pi'ivate-wiper of the side-switch is connected with the shaft private-wiper, with the ringer-relay-coil, with the back-bridgerelay-coil, and with a spring of the backbridge-relay.

7. A common battery automatic telephone exchange system comprising a subscribers line-circuit, a transmitter in said line-circuit, a receiver independent of but induetively connected with the said liiie-circuit, a ringing-key in the line-circuit, means for `opening the line circuit and grounding one side thereof when the ringing key is operated, means controlled by the switch-hook for controlling said ground connection, and a ringing relay deiiiergized when the ringing key is pressed for supplying ringing current to any called subscribers line, together with a centralized source of current for supplying current for talking purposes through the ringing-key and transmitter, said transmitter being disposed between the inductive connection and the ringing key.

8. A telephone system comprising an automatic exchange subscribers line. a source of talking current, a source of ringing current, a coiinectoi' provided with a ringer-relay for controlling the supply of talking current to the said subsciibers line, `and a local circuit for energizing said relay to close the talking circuit, the said connector having means including a privatewiper and private-bank-contacts for establishing a guarding liotential for any line with which the connector makes connections, said ringer-relay controlling the continuity of connection between the two lines and the fiow of ringing current to the called line.

9. A telephone system comprising a subscribers line, a centralized source ol talking current, a centralized source of ringing current, a connector provided with a ringer-relay adapted to control the supply of both talking and ringing current to the said line, and a circuit for energizing said relay to close the talking circuit, the said connector having means including a private-wiper and pri vate-bank-contacts for establishing a guarding potential for any line with which the connector makes connection, said ringer-relay controlling the continuity oi'v connection to the said line.

1t). A telephone system comprising a connector provided with -i'orinally open relavcontacts included in the path of theI voice-currents, a back-bridge-relay for the connector, said relay having one terminal permanently connected with one of said normally open relay-contacts, and said connector having means including a privatewiper and pi'ivate-bank-contacts for establishing a guarding potential for any line with which the connector makes connection.

11. A telephone system comprising a connector having release mechanism operated by a release-magnet, a ringer-relay for the connector, and an energizing circuit for said magnet, the said circuit being controlled by said relay, and said connector having means including a private-wiper and private-baiik-contacts for establishing a guarding potential for any line with which the connector makes connection.

12. A telephone system comprising a connector, a pair ot' line-relays, a ringerrelay, a source oie-talking curi'eiit, a source ot' ringing .urrent, and suitable connections whereby the ringer-relay when energized is adapted to connect the line-relays in series with the source oi' talking current, and to connect the said relays in parallel when deenergizeil. the said connecti'ir having means including a private-viper and private-bank-contacts for establishing a guarding potential for any line with which the connector makes connection.

13. A telephone system comprising a line-circuit, a connector provided with a pair of line-relays` and also with a releasemagnet and a ringer-relay, a source of talking current, a source of ringing current, and suitable connections whereby the ringer-relay controls tl'ie supply otl both talking and ringing current to the line-circuit, said ringer-relay being adapted when energized to connect the two line-relays in series with the source of talking current, and when denergized to connect the source of ringing current with the line-circuit, and the source of talking current with the line-relays in parallel, together with an energizing circuit for the said release-magnet, said energizing circuit being controlled by the ringer-relay, and said connector having means including a private-wiper and private-bank-contacts for establishing a guarding potential for any line with which the connect-or makes connection.

1-1. A telephone system comprising a connector having a double-wound relay adapted to be energized when its coiis are connected in parallel, and adapted to remain denergized when its two coils are connected in series, a line-circuit, a battery for supplying talking current through the said coils to the line-circuit, and a ringerrelay for the connector, together with an energizing circuit for the ringer-relay, said energizing circuit being controlled by said double-wound relay, and said connector provided with a private wiper and having means including said private-wiper and privatc-bank-contacts for establishing a guarding potential for any line with which the connector makes connection.

15. A telephone system comprising a connector, a line-circuit, a source of ringing. current, and a ringer-relay for the connector, said relay being adapted when denevgized to connect the ringing-generator with the liiie-circuit, the said connector having means including a private-wiper and private-baiik-contacts for establishing a guarding potential for any line with which the connector makes connection.

16. A telephone System comprising an automatic exchange subscribei"s line. a source ot' talking current, a source of ringing current, and a connector provided with a ringer-relay having normally open contacts in the talking circuit adapted to control the supply ot' talking current to the said subscribefs line, the said connector having a private-wiper, together with a lusy-releasc-circnit including said privatewiper.

17. A telephone system comprising a subscribers line, a centralized source of talking current, a centralized source of ringing current. and a connector provided with a ringer-relay having normally open contacts in the talking circuit adapted to control the supply of talking and ringing current to the said line, the said connector having a private-wiper. together with a lnisy-release-circuit including said private-wiper.

18. A telephone system comprising a connector provided with normally o )en switchcontacts included in the path ci the voicecurreiits, a liack-bridge-relay for the connector. said relay having one terminal permanently connected with one of said switch! contacts, and said connector having a private-wiper. together with a busy-release-circuit including said private-wiper.

19. A telephone system comprising a connector having release mechanism operated by a release-magnet, a ringer-relay for the connector, and an energizing circuit for said magnet, the said circuit being controiled by said relay, and the said connector having 

